1. Field of the Invention
The present invention relates to a wet-type electrophotographic image forming apparatus using a liquid developer. More particularly, the present invention relates to a wet-type electrophotographic image forming apparatus that includes a fitting unit and a developer cartridge for supplying developer to and collecting developer from a developing unit, and a method of setting up the same.
2. Description of the Related Art
Generally, electrophotographic image forming apparatuses can be classified as either dry-type image forming apparatuses that use a dry powder developer or wet-type image forming apparatuses that use a liquid developer. Dry-type and wet-type image forming apparatuses each have distinctive characteristics. Generally, wet-type image forming apparatuses have better print quality, with higher definition and resolution, than dry-type image forming apparatuses. As digital cameras have become more popular, the demand for color image forming apparatuses has greatly increased. They have especially increased demand for printers that produce high resolution, natural-color, prints.
To produce a desired level of print quality with a wet-type image forming apparatus, it is necessary to provide a developing unit with a larger amount of developer than the amount actually required for printing. For this reason, excess, unused developer is collected and returned to a developer cartridge. FIG. 1 schematically illustrates a conventional wet-type electrophotographic image forming apparatus that provides and collects developer.
As shown in FIG. 1, the conventional wet-type electrophotographic image forming apparatus includes a developer cartridge 10, a developing unit 40, and a fitting unit 30. The fitting unit 30 connects the developer cartridge 10 and the developing unit 40.
A first male fitting part 41 is disposed at the bottom of the developing unit 40, and a first female fitting part 12 is disposed at the top of the developer cartridge 10. The fitting unit 30 includes a second female fitting part 31 connected to the first male fitting part 41 of the developing unit 40, a second male fitting part 32 connected to the first female fitting part 12 of the developer cartridge 10, and a tube 33 for connecting the second female fitting part 31 with the second male fitting part 32, thereby creating a passage for developer. A supply pump 21 provides developer from the developer cartridge 10 to the developing unit 40 through a connection tube 22. The developer injected into the developing unit 40 is used in the image forming operation, and any remaining developer is returned to the developer cartridge 10 through the fitting unit 30.
To collect the wet-type developer, the printer must have a connection device for connecting the developing unit 40 to the developer cartridge 10. Because of the characteristics of wet-type developers, the connection device must seal tightly. In a conventional wet-type electrophotographic image forming apparatus, the first male fitting part 41 and the first female fitting part 12 are generally applied to the developing unit 40 and the developer cartridge 10, respectively. However, when the developing unit 40 is configured to include the first male fitting part 41, the developing unit 40 becomes bulky. This reduces the ability to use the developing unit as a consumable item. Furthermore, it complicates the assembly of the connection between the developer cartridge 10 and the developing unit 40 through the use of the fitting unit 30. That is, the first male fitting part 41 of the developing unit 40 must be connected to the second female fitting part 31 of the fitting unit 30 to connect the developing unit 40 with the fitting unit 30, and the second male fitting part 32 of the fitting unit 30 must be connected to the first female fitting part 12 of the developer cartridge 10 to connect the developer cartridge 10 with the fitting unit 30.
To address the above-described problem, the fitting part has been removed from the developing unit 40. A wet-type electrophotographic image forming apparatus using a developing unit without a fitting part is depicted in FIG. 2. As illustrated, the developing unit 40 includes an outlet 42 to discharge developer and an outlet lid 43. A fitting unit 30′ includes a collector 34, a tube 35, and a male fitting part 36. The male fitting part 36 is connected to or disconnected from a female fitting part 12 on the developer cartridge 10. Any developer remaining in the developing unit 40 discharges out the outlet lid 43 through the outlet 42 and passes through the collector 34, the tube 35, the male fitting part 36, and the female fitting part 12 to flow into the developer cartridge 10. With this configuration, when a user installs the developer cartridge 10, the user has to open the outlet lid 43 and connect the female fitting part 12 to the male fitting part 36 to thereby establish the connection between the developing unit 40 and the fitting unit 30′ and between the fitting unit 30′ and the developer cartridge 10.
With this configuration, although the fitting part of the developing unit 40 is eliminated, the outlet 42 and the outlet lid 43 are required instead. Thus, the developing unit 40 is still bulky. Also, it is still necessary to install the collector 34, thereby increasing the overall size of the wet-type electrophotographic image forming apparatus. Furthermore, this configuration reduces the security and preciseness of the connection between the developing unit 40 and the fitting unit 30′.
Accordingly, there is a need for an electrophotographic image forming apparatus with an improved fitting unit between a developer unit and a developer cartridge.